In one aspect, the invention relates to a collar device. In another aspect, the invention relates to the use of a collar device to protect a drill pipe during drilling operations. In yet another aspect, the invention relates to a method for forming a composite drill collar device from a reinforced plastic.
In the drilling of wells, for example, oil wells, a hollow drill pipe string positioned in a drill pipe casing is often used. A bit is positioned on the end of the drill pipe strong. Mud flows down the hollow drill pipe string, past the bit, and up the annulus between the drill pipe string and the drill pipe casing to carry away cuttings produced by the bit. In the absence of collar devices positioned on the drill pipe string, dragging of the drill pipe string on the inside of the casing during the drilling process can result in damage to either or both of the drill pipe string or the drill pipe casing. Collar devices can be fitted to either/or both of the drill pipe string or casing to mitigate such damage. Since the collar devices can become damaged, it is desirable that they be attached to the drill pipe string to facilitate their removal and replacement if required. It is often not feasible to form the collars from highly damage-resistant materials such as steel because in such case the collar itself would be capable of damaging the drill pipe string or drill pipe casing. To massively construct the collar to resist damage is often not feasible because large sizing would impede the flow of mud up the annulus and interfere with the drilling of the well. Thermoset materials are not entirely suitable because of their brittleness. Common thermoplastic materials are not suitable in many applications because of their softness and low temperature resistance.